Applied behavioral analysis (ABA) is an intensive, one-on-one treatment in which a therapist observes a child and then develops an individualized plan to teach missing social behaviors, such as making eye contact and responding to others, by using a stimulus, response and reward approach. For instance, she may ask the child to say "hello" to his mother. The therapist will demonstrate by saying "hello." If the child doesn't respond, the therapist will ask again; she may even turn the child toward his mom. Repeating the stimulus and response, she will reward every step toward the desired behavior—for example, if the child turns and looks at his mom. ABA typically involves 20 to 40 hours of therapy per week.